Why is there no f6 tornado?

Related questions

1. Can you feel a skyscraper sway?
2. Why is it called a Quonset hut?
3. How much does a steel garage cost?
4. Are Quonset huts tornado proof?
5. Can a skyscraper survive a tornado?
6. Can tornado destroy concrete house?
7. How are Quonset huts measured?
8. Are there tornado proof houses?
9. How much are steel master buildings?
10. Is a bathtub safe during a tornado?

Tags

1. #added
2. #scale
3. #speeds
4. #expected
5. #severe
6. #unprecedented
7. #tornadoes
8. #actual
9. #damage
10. #reach
11. #produce
12. #would
13. #given
14. #leaves
15. #tornado
16. #observed
17. #range
18. #rating